Page 110 - Predicting survival in patients with spinal bone metastasesL

CHAPTER VII
One aims to prevent that patients treated with radiotherapy will undergo an adverse event in their follow up. Thus, especially in this heterogenous patient group in terms of amongst others primary tumor, physical condition and referring physician, in which a limited risk of spinal instability is expected, it is of utmost importance to identify those patients who, after radiotherapy, underwent an event and perhaps would have gained more in terms of sustaining quality of life if a surgical stabilizing procedure had been performed instead of radiotherapy. By including only patients treated with radiotherapy, we focused on this clinically important group in which there is some clinical equipoise. Therefore, leaving out patients who were primary stabilized did not result in major selection bias.
Strengths of the study are the number of observers and the fact that highly experienced clinicians of four different medical disciplines involved with treatment of SBM were represented. Although there was limited agreement between the four observers, our panel’s constitution reflects clinical practice as in everyday reality spinal instability is often assessed separately by individual clinicians. Although a multidisciplinary meeting would seem most fitting to discuss instability and agree on appropriate treatment, due to the often swift course of disease and symptoms, such weekly meetings take place too late. Also, the endpoints used are clinically relevant. Whereas other validation studies compared the SINS outcome to predetermined consensus-based cases of stable and unstable spines, in the current study, actual clinical data were used as outcome measure.
Even though the authors agree that the components constituting the SINS classification are potentially important factors to consider when assessing spinal instability, in its current form, clinical applicability seems limited. As a tool for streamlining communication between physicians of different medical specialties and facilitating the decision making concerning surgical consultation, the SINS could be useful.
A prospective CT-based study with clear clinical endpoints might help determine the relative importance of each component in predicting complications resulting from spinal instability and could result in an adjustment of the points allocated to each component, as well as the grouping of each variable. As this study and the study performed by Teixeira et al.8 have shown, panels consisting of reviewers from different medical specialties can result in lower levels of agreement, whereas
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